How to change only text inside a div which has other divs

Question

I have html below. What I want to do depends on some conditions. I want to keep changing the text which is Sometitle.

<div id="header">
    Sometitle
    <div>
        <div>
            aa
        </div>
        <div>
            bb
        </div>
    </div>
</div>

I tried using Jquery below but it removes the other divs also.

$("#header").text("Its a thrusday today !");

How do I get this done? I cannot modify this HTML in any case. I just have to use jquery and get this thing done.

Here is a jsfiddle I created : http://jsfiddle.net/qYUBp/

Answer 1

If you dont want it in a single line.

var tmp=$("#header>div").html();
$("#header").text("its thursday").append('<div>'+tmp+'</div>');

jsfiddle